The ultimate goal is to elucidate at the molecular level the mechanism of leukemogenesis by AMV in chicken hematopoietic cells. Research objectives for the coming years are: Identification and characterization of the defective AMV genome responsible for acute myeloblastic leukemia. Investigation of biological activity of a presumptive AMV provirus isolated from leukemic cells. Characterization of the lukemogenic viral sequences (gene?) and of the putative product.